@i am moving forward
I went through all of this about eight years ago. I was the one who initiated our breakup, and as funny as it sounds the first few months were great, even though we were still living in the same house, because I felt a sense of autonomy and control I'd never had in our marriage.
Then about 4 months in, it started to hit me. This was real and it was really happening. The next 6 months or so were a total hell, I lost almost 50 pounds in 4 months, I screwed up so much at work I almost lost my job, and I spent most of that time practically begging my wife to try again. I'm lucky I had a couple of really close friends who talked me off the ledge time and time again because I don't know what I would've done without them.
In the midst of all of it, one if my friends (who had gone through a divorce) told me, "A year from now you are going to feel better...". I didn't believe him but then I realized that as the days, weeks and months went on, he was right. There was still a lot of pain, of course, and tons of regret, especially because we had two kids who were 12 and 8 at the time, but I realized as all of that time went on I just felt "better". Once you reach that point you will know what I'm talking about.
That doesn't mean the pain and regret don't disappear. I'm remarried to a wonderful woman and have a great relationship with my kids, but I still think a lot about what happened. It is kind of like losing someone close to you, you find a way to live with it, but you never get over it.
Better days are ahead, just focus on getting yourself back to where you want to be and focus on making sure the kids are working through it as best they can too. I also had an awesome counselor that was a big help. Most of all, don't let yourself get drawn into any divorce BS, like arguing about stupid stuff, and think about how to create a life in what is the here and now.
Divorce does suck, and even though I am in a way better place in my life now because I did it, I wish I hadn't have gone through it. But focus on the future and not the past, and control the things you can control. Just trust that time will give you clarity, because it always does.